Etude de nanofils de silicium comme matériau d'électrode négative de batterie lithium-ion

Abstract : Silicon is a promising anode material to increase the capacity of Li-ion battery. Unfortunately, it undergoes huge volume variations upon cycling, leading to fast capacity decay of the electrode. One of the keys to overcome this issue is to use silicon nanowires (SiNWs), synthesized by chemical vapor deposition, which have the ability to better accommodate the volume changes. The thesis presented here aims at studying the electrochemical performances of such electrodes and the possible improvement in the perspective of a use in a Li-ion battery. First of all, analysis by nuclear magnetic resonance (NMR), electron energy loss spectroscopy and electronic tomography were performed along the first cycle in order to study lithium insertion and extraction in this material. Different strategies were then addressed to reach a better cycle life, and ex-situ analysis by electron microscopy and NMR allowed a better understanding of the electrode ageing, by notably pointing out the continuous electrolyte degradation. This is at the origin of irreversible lithium consumption which is not compatible with a cycling in a full Li-ion cell. The silicon electrode prelithiation appears as a promising way to overcome this issue. Another important barrier for the elaboration of full Li-ion batteries with high energy density is the low surfacic capacity of SiNWs electrodes. New electrodes based on a silicon nano-tree structure were then synthesized to reach higher silicon loading and allowed to increase the surfacic capacity of the electrodes by a factor 6. Hence, this work gives new insights for the elaboration of high energy density Li-ion battery using a nanostructured silicon anode.
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Submitted on : Monday, November 30, 2015 - 4:09:02 PM
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  • HAL Id : tel-01234963, version 2

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Leveau Lucie. Etude de nanofils de silicium comme matériau d'électrode négative de batterie lithium-ion. Physique [physics]. Ecole Polytechnique, 2015. Français. ⟨tel-01234963v2⟩

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